Tabnapping attack baits phishing trawl

A leading developer of Firefox has warned of a sneaky potential new form of phishing attack.

Aza Raskin, the creative lead for Firefox, explains that the approach exploits the fact that most surfers keep many tabs open during a browsing session, without really keeping track of what sites they have visited.

The so-called tabnapping attack works by using JavaScript to switch the destination page in a tab after a few seconds of inactivity. This might be done using attack script planted in an otherwise legitimate website, for example.

If a surfer has only one tab open he is likely to get suspicious if a browser seems to be pointing at Gmail or other potential target rather than a news site, for example, and double check. But this is far less likely to happen if a user has multiple tabs open and where he might easily be induced to log in again, handing over login credentials to an attacker in the process.

The potential attack might be customised using a surfer's browser history file, Raskin warns. "Using my CSS history miner you can detect which site a visitor uses and then attack that. For example, you can detect if a visitor is a Facebook user, Citibank user, Twitter user, etc, and then switch the page to the appropriate login screen and favicon on demand," he explains.

Raskin has posted an explanation of the attack in a blog post here (watch what happens after you leave the page for a few seconds) and in a video explanation uploaded to Vimeo (below).

He suggests that improving browser technology that remembers login credentials for websites is one approach to help combat the problem. At best this is a partial solution, though, since many users avoid using password management in general; and saving passwords is an extremely bad idea when using computers in libraries or even at work that are shared by multiple users. ®